The present invention relates generally to a cable used preferably for connections between electronic video and audio components. More particularly, the present invention relates to shielded coaxial, fiber optic and other cables.
Cables used in connecting video components to each other and to cable outlets have generally been of the coaxial variety. Such cables generally comprise a main conductor, some shielding elements, a ground conductor and an external plastic insulating material all generally formed in an elongated cylindrical configuration. While adequate signal transmission has been achieved with such cables, modern uses for cables requires that a variation in the sizes and shapes, particularly of the cross-sectional shapes, of such cables be available.
Unfortunately, the nature of such cables and electrical transmission of signals do not generally lend themselves to cables having a cross-sectional shape other than round. It has been found, generally, that the use of non-circular cross-sectional cables leads to magnetic and static interference in the cable. Such interference is translated into a diminution of the signal. In some instances signal loss is great enough to eliminate the benefits of cable transmission of signals.
Further, it has been found that the use of cables having round cross-sections limits the placement of cables. For example, round cables can not be placed on floors as they are subject to rolling and are likely to cause an individual to trip if stepped upon. Placement of cables beneath rugs or carpeting causes unsightly lumps to appear in the floor covering and can lead to premature wear and tear on the floor covering. Further, such cables can not be attached to a wall or ceiling without the use of unsightly fasteners, such as cable nails or U-shaped fasteners.
It has also been determined that transmission through such cables occurs in a generally star-shaped (at the cross-section of the cable) pattern with signal bouncing inside of the cable and traveling in a somewhat cork-screw pattern along the length of the cable. As a result, co-axial cables made with a round cross-section have been most successful in transmitting signals without creating interfering transmissions.
I have invented a cable that can be made with a variety of cross-sections other than round without a loss of signal strength or diminution of the signal as a result of inadequate or improper shielding. I have found that the signal transmitted in the cable of the present invention generally travels about planarly in a zig-zag like pattern. As a result the cable of the present invention provides signal transmission at the level of the finest co-axial cables without generating errant interfering transmissions.
Other objects and advantages of the present invention will become apparent as the description proceeds.
The present invention concerns an insulated cable shielded for transmission of RF, comprising a central conductor having an intermediate insulating layer that substantially covers the central conductor. The cable further includes a first discrete shielding layer consisting of a homogeneous electrically conductive material that substantially covers the intermediate insulating layer and shields the central conductor from RFI. A second discrete shielding layer consisting of a homogeneous electrically conductive material that substantially covers the first shielding layer and shields the central conductor from EMI are also included. Further, an outer insulating layer that substantially covers the second shielding layer and protects the insulated cable from damage by external forces, wherein the insulated cable has a noncircular cross-section.
In a preferred embodiment of the insulated cable of cable has a noncircular cross-section and a thickness of less than about 0.10 inches. The insulated cable of the preferred embodiment has a generally rectangular cross-section. It has been determined that the insulated cable of the preferred embodiment, because of its noncircular cross section carries a signal by radiating the signal within the cable from a center conductor in a zig-zag like pattern.
In the preferred embodiments of the present invention the cable is provided with shielding elements that allow the non-circular cross-section with no diminution in signal strength or interference. The cable can be manufactured in a variety of shapes without having signal strength or shielding problems. Such shapes as rectangular, flat, semi-circular or having the shape of certain moldings generally used in wall decorations are possible. The present invention allows for such cables, which can have relatively thin cross-section, to be flexible such that they can be bent to follow the contours of a wall, ceiling, floor or other surface. Further, as the cable of the present invention has a generally flat surface along a length of the cable, the cable can be attached to any surface by the use of adhesives, including adhesive tape or glue. The wiring system includes a connecting module, an insulated cable, and a plug assembly.